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Subtracting a Whole Number from a Fraction

BY rq6bf
July 16, 2025
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Class Notes: Subtracting a Whole Number from a Fraction

Objective

Learn how to subtract a whole number from a fraction by converting the whole number into a fraction and using common denominators.


Steps for Subtracting a Whole Number from a Fraction

  1. Write the Whole Number as a Fraction

    • Example: (2 = \frac{2}{1})
  2. Convert to Common Denominators

    • Multiply the whole number fraction so the denominators match.
  3. Subtract the Numerators

    • Once denominators are the same, subtract the numerators and keep the denominator.

Example 1

Problem:
(\frac{14}{3} - 2)

  • Convert 2 to a fraction:
    (2 = \frac{2}{1})

  • Match denominators:
    Multiply (\frac{2}{1}) by (\frac{3}{3}):
    (\frac{2}{1} \times \frac{3}{3} = \frac{6}{3})

  • Subtract:
    (\frac{14}{3} - \frac{6}{3} = \frac{8}{3})

  • Answer:
    (\frac{8}{3}) (improper fraction)


Example 2

Problem:
(\frac{3}{4} - 5)

  • Convert 5 to a fraction:
    (5 = \frac{5}{1})

  • Match denominators:
    Multiply (\frac{5}{1}) by (\frac{4}{4}):
    (\frac{5}{1} \times \frac{4}{4} = \frac{20}{4})

  • Subtract:
    (\frac{3}{4} - \frac{20}{4} = \frac{-17}{4})

  • Answer:
    (\frac{-17}{4}) (improper fraction)


Key Points

  • Always write the whole number as a fraction over 1.
  • Find a common denominator by multiplying as necessary.
  • Subtract the numerators once the denominators match.
  • The final answer will be an improper fraction.